I read a bit and found varying voltage figures for what the TPS readings should be. Power from the computer is 5.01V, ground is good and from the blue wire runs from .47v to 4.37v in it's range of motion with no fluctuation while tapping it, back probed with the engine warm (not running). These numbers are a bit lower than the figures I saw, but now a whole lot lower, would it justify replacing the TPS as a culprit for my high idle rpm?

Thanks

 

I wouldnt replace it. Have you looked at all the other obvious causes? Vacuum leaks ect? Are there any codes present?

 

The TPS sensor just feeds information to the PCM about the throttle position, it cannot physically alter throttle position or affect idle speed unless it is installed incorrectly. If the TPS hasn't been removed and the condition just came about, I doubt that it is installed incorrectly.

I agree with the above. You need to check to see if anything is physically hanging the throttle open or allowing more air into the engine through other means (vacuum leak, faulty or stuck IAC valve).

 

Cleaned the throttlebody today, it was filthy. I also took apart and cleaned the iac, it was encrusted so I thought it wouldnt seat properly. The only thing I did today that helped was changing the pcv valve, that dropped my rpm by 300 down to 1700. I think I found my vacuum leak though, at the front of the intake manifold, when I spray tb cleaner there the rpm's go up.

 

Sounds like you have found the source of the problem. Let us know if we can be of further assistance with the plenum gasket change.

 

Im glad you for the problem without throwing lots of parts at it! Congrats!

 

Well, looking into it there may be more to the issue. On the front passenger side of the upper intake manifold one of the bolts is snapped right off, just sitting in the hole, but the leak doesnt seem to be coming from there, but rather some sort of cylinder at the front of the manifold below the coolant hose, I'll try to get a pic later. everything else around there is dirty but this is clean so maybe they re-used an old gasket or something.

I still think the TPS needs replacing though, if I give it a bit of gas it doesnt know what gear to be in.

 

I believe you are talking about the EGR valve. If there is a leak here, it could cause both an exhaust leak as well as a vacuum leak.

 

Think I got it, the tip off was that the EGR was much cleaner than everything else. I took it off and the mating surface on the manifold was all gouged, the previous owner no doubt used a screw driver or metal scraper to remove the old gasket material. I put on a thin layer or permatex sealer on both sides of the gasket and we'll see in the morning when the sealant is cured, I'll re-connect the battery in the morning... Here's hoping...

 

Well, cold idle is down to 1100-1200 RPM with the gasket re-sealed, but it still climbs when idling so that was obviously part of the problem, but a 600 rpm drop in cold idle is a good continuation to fixing this neglected Jimmy. Gonne pull a TPS from the pick n pull since my voltages are out of spec and gonna get an IAC from there too if I find one that looks new.